Repair couplings are used in the maintenance of piping systems to repair sections that may be damaged or otherwise need to be removed for some reason. Repair couplings are made to connect to the ends of pipes in a linear fashion.
Repair couplings are most common in the repair of PVC and other plastic pipes. PVC repair couplings are typically made with ends that can be solvent cemented to either sections of pipe or to fittings.
Repair couplings of the prior art are made with (i) an elongate, hollow body having a smooth bore and (ii) an interior tube slidably disposed in telescoping fashion within the smooth bore. O-rings are disposed around the circumference of the interior tube to seal the interior tube to the interior surface of the body, while allowing axial movement of the interior tube back and forth within the body. The interior surface of the body is lubricated to facilitate such axial movement.
One problem with repair couplings of the prior art arises after several weeks of storage, when the O-rings begin pushing through the lubricant, resulting in dry interference between the O-rings and the interior surface of the body. This makes it very difficult to axially slide the interior tube within the body.
A second problem with plastic repair couplings (such as PVC repair couplings) of the prior art arises in the welding process. In the welding process, after adhesive is applied to the exterior surface of the distal end of the interior tube, and after the distal end of the interior tube is inserted into the end of a pipe section, the interior tube must be turned at least one quarter turn within the pipe section to properly distribute adhesive between the interior tube and a pipe section. Since the body of the repair coupling surrounds much of the interior tube, and since the distal end of the interior tube is smooth, gripping the interior tube to effect the turning of the interior tube within the pipe section can be difficult.
Accordingly, there is a need for a repair coupling which avoids the aforementioned problems in the prior art.